####018007724#### FXUS65 KRIW 152240 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 440 PM MDT Wed Jul 15 2026 .KEY MESSAGES... - Scattered showers and thunderstorms are forecast this afternoon and evening across western and northern Wyoming. Localized heavy rainfall and gusty winds are possible in any thunderstorms. - More shower and thunderstorm chances Thursday through Saturday for western and northern Wyoming. This potential becomes more widespread across the state Sunday through the middle of next week. - Hot temperatures are expected through Sunday with highs in the upper 80s to upper 90s. && .UPDATE... Issued at 1200 PM MDT Wed Jul 15 2026 The forecast for today is on track with showers and thunderstorms over western and northern Wyoming as a shortwave traverses overhead. As of 18Z/12PM, the shortwave is located over eastern Idaho and will continue northeastwards within the southwesterly flow aloft. Across the western valleys, morning cloud cover is expected to limit the overall coverage of thunderstorms early this afternoon. Shower and thunderstorm coverage should be greatest from the Gros Ventres and Wind River Mountains to the Absarokas and Yellowstone due to favorable orographics and sufficient daytime heating. Thunderstorms then move into the Bighorn Basin and upper Wind River Basin after 3PM. A few thunderstorms could become severe across the northern Bighorn Basin due to proximity to the shortwave and over 1,000 J/kg of BLCAPE. With DCAPE values around 1,200 J/kg, gusty winds up to 60 mph will be the primary severe threat. There is an additional threat for localized heavy rainfall, but as mentioned in the morning discussion, the flash flooding threat is on the lower end due to the storms moving. Thunderstorms will begin to diminish in coverage after sunset, with only lingering showers and thunderstorms through 1AM along the shortwave axis from the northern Bighorn Mountains to southern Lincoln County. Otherwise, the forecasted shower and thunderstorm chances continue Thursday through the middle of next week. && .DISCUSSION... Issued at 133 AM MDT Wed Jul 15 2026 I am coming off of a short break. When I left Sunday morning, I was talking about all time record high temperatures. And we had several across the area. What a difference 72 hours makes. Now, we are talking about a much more moist atmosphere and the potential for heavy rain and possible flash flooding over the next several days. The reason is that the monsoon is now here. We had a few showers out there yesterday and a couple of light ones right now, but for the most part most of the action is in Montana right now. Most of the models, both the synoptic and convective ones, have the main area of action across the northwestern half of the area, largely west and north of a Buffalo to Riverton to Evanston line. And, all models show the most numerous storms over the northwestern Bighorn Basin and the Absarokas, where the combination of a passing shortwave and some low level easterly upslope flow will bring more numerous storms. The big difference today is the amount of moisture in the atmosphere. Climatologically, precipitable water values are the highest around this time, averaging around 0.60 inches in Riverton. Today, some of these will exceed this by 150 to 175 percent, especially in the aforementioned Bighorn Basin where values may climb as high as 1.30 inches, close to 200 percent of normal. Instability parameters are also decent here, with lifted indices of minus 4 and CAPE over 1000 J/kg, so we could see a stronger storm as well. The main threat will still be heavy rain though. If there is one thing against flash flooding, it is that there is some decent flow at 500 millibars so the storms will be moving somewhat. This looks like a diurnal event, with the vast majority of storms ending by sunset and almost all done by midnight. And, it will be another hot day. Probably not record breaking, but some of the hotter locations could approach 100 degrees again this afternoon. At this time, Thursday looks fairly similar to today, with mainly diurnal showers and thunderstorms and in roughly the same locations. The deeper moisture may press a little further to the east, but areas like Casper and Rock Springs continue to look mainly dry. Precipitable water values also look fairly similar, generally 150 to 175 percent of normal across the northwestern half of the area, along with easterly upslope, and the maximum chance of convection in the easterly flow upslope locations. I think the chance of local flooding may be greater on this day though, since flow in the 700 to 500 millibar layer looks lighter, so storms would be slower moving. Also, temperatures should continue to be on the downward trend, although it will still be above normal with widespread 80s and 90s for highs. The latest guidance now shows ridging building back over Wyoming Friday and Saturday, with 500 millibar heights rising anywhere from 20 to 40 meters. Precipitable water values also drop about 10 to 20 percent, but this still averages around 150 percent above normal. The result will be somewhat less coverage of storms and the main areas of storms being pushed a bit further to the west, although all locations have at least some chance. The emphasis will again be on easterly upslope locations (noticing a pattern here). The mean 700 to 500 millibar flow is also stronger, so the threat of flooding may decrease a bit with better steering flow and a slightly, emphasis on slightly, less moist atmosphere on these days. Temperatures will also increase somewhat on these days, with some 100s again possible in the eastern Bighorn Basin. The main chance of storms may finally begin to shift east of the Divide on Sunday as the main area of moisture moves eastward as the core of the ridge moves southeastward and moisture can be pushed further east. There is still a bit of a spread on exact timing of this happening and it is impossible to pinpoint a more active day this far out. However, the eastern portions of our area may finally begin to get some needed moisture next week. As for temperatures, they look to remain above normal but more cloud cover and the core of the ridge moving away should keep record high temperatures away for now. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 440 PM MDT Wed Jul 15 2026 Thunderstorms continue to move north-northeast across western WY this afternoon, with the main impacts on KCOD/KWRL the next few hours. Some lingering showers may return or reach KBPI/KPNA and KRIW/KLND through 05Z, but most precipitation should be decreasing after sunset with loss of daytime heating. Skies will remain partly cloudy through the night, with generally light winds. Thursday will see another round of showers and thunderstorms during peak heating hours in the afternoon. Thunderstorms may be more isolated than today, but the threat for storms remains for all sites expect KCPR. Have introduced PROB30 groups for the afternoon for -TSRA in the vicinity. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Gerhardt DISCUSSION...Hattings AVIATION...Straub/LaVoie ####018008371#### FXUS61 KCLE 152244 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 644 PM EDT Wed Jul 15 2026 ...00z TAF Aviation Forecast Update... .WHAT HAS CHANGED... The potential for thick wildfire smoke continues to increase tonight and Thursday, and there is growing potential for it to linger through at least Friday. Chances for showers and thunderstorms continue to increase late Friday and Saturday, but Sunday has trended dry. && .KEY MESSAGES... 1) Hot conditions will continue through Saturday, but the humidity will temporarily drop for Thursday and Friday leading to lower heat indices in the upper 80s to low 90s. 2) Wildfire smoke to affect the region tonight and Thursday leading to poor air quality, which could linger through Friday. 3) Periodic showers and thunderstorms are expected Friday through mid next week. The greatest potential for organized storms is late Friday and Saturday. && .DISCUSSION... KEY MESSAGE 1... The center of the anomalous 600 DAM H5 ridge has shifted to a position from the corn belt through the Ohio Valley this afternoon, with satellite and water vapor loops showing a band of moisture associated with convection dropping southeastward through the northern and central Great Lakes on the northern edge of this ridge. This band of clouds and scattered showers/thunderstorms will continue to sag toward the area this evening and tonight as a weak cold frontal boundary sags across Lake Erie and NW PA and eventually through northern Ohio by Thursday morning. Strong mid-level capping is in place beneath the ridge this afternoon characterized by 700 mb temps of 12 to 14 C and a defined EML, so despite strong instability (MUCAPE over 4000 J/Kg on the latest Mesoanalysis), not sure that the weak approaching front can sufficiently breach the cap to get any convection into our area. The 12Z runs of the HREF and RRFS backed off on the thought of isolated convection early tonight, but given the instability, kept slight chance POPS in the 00 through 06Z timeframe for an isolated cell or two dropping across the lake. Otherwise, the main impact of the weak cold frontal passage tonight will be a 5 to 10 degree drop in dew points. Air temperatures will remain hot Thursday and Friday (mid 80s to low 90s), but the brief influence of surface high pressure building into the northern and eastern Great Lakes will advect drier low-level air into the area, keeping dew points in the upper 50s to mid 60s. This will limit heat indices to the upper 80s/low 90s Thursday and Friday. A strong mid/upper shortwave progressing from the northern Plains into the Great Lakes late Friday and Saturday will lift the frontal boundary back northward as a warm front, and this will bring the sticky air (dew points over 70 F) back into the region for Saturday to go along with one more hot day. More on that system in key message 3 below. KEY MESSAGE 2... The most unique element of this forecast is growing concern for thick wildfire smoke tonight and Thursday, possibly lingering through Friday. Wildfires continue to burn in northern Minnesota and central Ontario Province, and visible satellite loops today have been showing the smoke plume funneling east/southeast across the northern and central Great Lakes and New England in the NW flow on the northern edge of the mid/upper ridge. The frontal boundary is helping to converge and bring this plume to the surface, and surface observations and webcams in northern Lower Michigan have shown very poor visibilities today. As the frontal boundary sags into the area tonight and Thursday, the smoke plume is expected to sag in as well. The 12Z HRRR and RRFS were more aggressive with smoke density and visibilities late tonight through Thursday night, so smoke coverage has been increased in the forecast during that time. This may support visibilities as low as 1 to 3 miles at times, as well as very poor air quality. People are encouraged to limit time outdoors Thursday. At least patchy smoke could linger Friday given a continuation of NW flow aloft, but confidence is lower beyond the time range of the HRRR and RRFS, so kept it out of the forecast Friday for now. KEY MESSAGE 3... As mentioned above, a strong mid/upper shortwave trough will progress from the northern Plains through the Great Lakes late Friday and Saturday. This system will finally shunt the large mid/upper ridge southwest into the southern Plains and Rockies, with a strong cold frontal passage Saturday evening or Saturday night. The old frontal boundary will lift back north as a warm front Friday night and early Saturday in response to the approaching shortwave and associated surface low. As this front lifts back north, a 30+ knot low-level jet and associated strong theta e advection could trigger an MCS across the central Great Lakes Friday night. Depending on the evolution and track of this complex, some showers and thunderstorms could spill into the region Friday night and early Saturday. The more likely timeframe for organized convection will be along and ahead of the cold front Saturday evening. Moderate to strong instability is expected in the warm sector, and given what looks like a dynamic shortwave trough for mid summer (moderate to strong mid level flow), severe weather and heavy rainfall is possible. The amount of instability will be influenced by how much debris cloudiness and showers get into the area Saturday morning from the prior MCS. Given the set up, would anticipate our CWA to be included in a future severe weather outlook from the SPC for Saturday. Canadian high pressure will bring cooler, drier, and less humid conditions Sunday and Monday, but chances for showers and storms will return late Monday and Tuesday as another cold front drops through the area. Mid/upper troughing deepening across the eastern CONUS through the middle of next week will allow progressively cooler air to build in, and temperatures will be below normal for a change. && .AVIATION /18Z Wednesday THROUGH Monday/... The main message for this 00z TAF update will be VFR conditions this evening but widespread wildfire smoke will move into the area overnight through Thursday. We have 3sm to 5sm haze and smoke in the TAF for all sites starting later tonight through the day on Thursday. There is some potential for pockets of IFR smoke of 1sm to 2sm at times on Thursday, especially across NEOH and NWPA. Winds will be from the west this evening 5 to 8 knots becoming northerly on Thursday. Outlook...Non-VFR visibility possible through Friday due to Canadian wildfire smoke. Non-VFR likely Friday night through Saturday night in showers and thunderstorms. && .MARINE... Southwest winds across Lake Erie of 5-10 knots this afternoon will diminish to 5 knots or less this evening in to the overnight hours as a weak cold front sags south across the lake. Behind this boundary, winds will become northerly at 5 to 10 knots into Thursday night, resulting in waves across the nearshore to build to 2 feet or less. A warm front will lift north late Friday into early Saturday, allowing for south- southwest winds of 10-15 knots to develop. A cold front will quickly follow late Saturday into Sunday with winds sustained at 10-15 knots but shifting to become more northerly. During this period, waves across the central basin will build to 2-4 feet, possibly needing a Small Craft Advisory for part of Sunday. An active weather pattern continues into next week, resulting in numerous wind shifts and periods of waves between 2 and 4 feet. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Heat Advisory until 8 PM EDT this evening for OHZ003-006>011- 017>023-027>033-036>038-047. Air Quality Alert from 7 AM Thursday to midnight EDT Thursday night for OHZ003-006>014-017>023-027>033-036>038-047-089. PA...Air Quality Alert from midnight tonight to midnight EDT Thursday night for PAZ001>003. MARINE...None. && $$ DISCUSSION...Garuckas AVIATION...77 MARINE...04